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CHAMBERS'S

INFORMATION FOR THE PEOPLE.

NEW AND IMPROVED EDITION.

CONDUCTED BY

W. AND R. CHAMBERS,

EDITORS OF CHAMBERS'S EDINBURGH JOURNAL, EDUCATIONAL COURSE, &c.

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SOLD BY

W. S. ORR AND COMPANY, LONDON; W. CURRY JUNIOR AND
COMPANY, DUBLIN; AND ALL BOOKSELLERS.

PRICE TENPENCE.

The First Volume being now complete, purchasers are informed that cloth covers, with a handsome an
suitable design, may be procured of the Publishers, or through any Bookseller.

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THE "INFORMATION FOR THE PEOPLE," published in 1833-4, consisted of fifty sheets in large quarto, each (with a few exceptions) containing a summary of a particular branch of human knowledge. The large sale which this work continues to experience as a volume, has suggested to the Editors the propriety of throwing it into the more convenient form of royal octavo, and at the same time extending and improving its contents.

They have therefore respectfully to announce, that the issue of AN EXTENDED AND IMPROVED EDITION OF THE "INFORMATION For the People" was commenced on the first Saturday of January 1841, and will continue, at the rate of a sheet every Saturday, till the work is completed. It will consist of 100 sheets, or double the former number, and treat more than double the former number of subjects. The existing articles will be in many instances re-written, and in all so much improved, that the work, considering at the same time its being so much extended, may, without much impropriety, be described as one altogether new. The New Series will also have the advantage of an arrangement of subjects in some degree accordant with their natural order, and it will be more extensively illustrated by Wood Engravings. Completed in two volumes, containing 1600 doublecolumned pages, at the price of twelve shillings and sixpence, it will be a COMPREHENSIVE POOR MAN'S CYCLOPEDIA, AND PERHAPS THE MOST STRIKING EXAMPLE YET GIVEN OF THE POWERS OF THE PRESS IN DIFFUSING USEFUL KNOWLEDGE.

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Published by W. and R. CHAMBERS, Edinburgh; W. S. ORR and COMPANY, London; W. CURRY, Jun. and Co., Dublin. and sold by all booksellers who usually supply Chambers 8 Journal.

CHAMBERS'S

INFORMATION FOR THE PEOPLE.

CONDUCTED BY WILLIAM AND ROBERT CHAMBERS, EDITORS OF CHAMBERS'S
EDINBURGH JOURNAL, EDUCATIONAL COURSE, &c.

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NATURAL PHILOSOPHY is a term of wide import, and has
a reference to all those branches of physical science
which treat of existing substances, their motions, their
mutual connexion, and their influence on each other.
In this enlarged sense it may be considered as embrac-
ing astronomy, mathematics, dynamics, hydrostatics,
geology, chemistry, optics, botany, in short, a vast range
of human knowledge, which for the sake of convenience
is usually divided into distinct branches of science. In
its more limited and ordinary meaning, the term applies
only to inorganic substances, and the laws which regu-
late their connexion with each other, but without alte-
ration of character; and it is this most important branch
of knowledge, which in reality is the basis of all others,
of which we now propose treating. We shall commence
with an explicit definition of the meaning of the term
substances or matter, it being necessary that this be
clearly understood.

MATTER AND ITS PROPERTIES.

Matter-or that of which all bodies are composed whose existence is made known to us by means of the senses or by the test of philosophic experiment-is possessed of various properties, some of which are essential to its existence, while others are only accidental or contingent. The essential properties of matter are Impenetrability, Extension, Figure, Divisibility, Inertia, and Attraction.

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bodies may have the same volume, but possess very different figures. Thus, two masses of matter may have the same volume, although the one be round and the other be square.

Matter is divisible into parts, and these parts may again be subdivided into other parts. By this is meant divisibility or separability. To the practical subdivision of matter there seems to be no assignable limit; and many of the instances of it which may be found in philosophical investigations almost exceed credibility. The thinnest part of a soap-bubble, which is a thin shell of water and the matter of soap, does not exceed in thickness the 2,500,000th part of an inch. The useful arts, also, furnish many striking examples; but it is in the organised world that the most astonishing proofs of the extreme divisibility of globules, or particles of matter, are to be found.

Animalcules-that is, animals which are so small as to be invisible to the naked eye, and which, by means of microscopes, are seen floating in water-are in some cases so minute, that it would require a million of them to form the bulk of a grain of sand. As these animalcules possess, in every case, a perfect organisation to enable them to perform all the functions of life, the smallness of their different parts, and the extreme minuteness of the particles of matter which compose them, are too exquisite to be made the subject of calculation: the imagination is lost in the contemplation of their wonderful economy. The effluvium or odour which excites the sensation of smell, consists of an incalculable number of particles of matter floating in the atmosphere, and so minute as to be altogether invisible to the eye. These particles are not more remarkable for their inconceivably small size than for the length of time which they will remain in suspension in the atmosphere, or in connexion with some particular place. The effluvium given forth by a single grain of musk has been known to perfume a large apartment for twenty years, and yet at the expiry of that period there was no sensible diminution of the little mass of matter from which the smell had proceeded.

Impenetrability is that quality of bodies, in virtue of which each occupies a certain portion of space, and excludes other bodies from existing in the same place at the same instant. In the usual sense, we call any hard body, such as a stone, impenetrable, because it firmly resists our efforts to pierce it. But as it is understood philosophically (although we can condense, pierce, and remove the greater number of them), all bodies are alike impenetrable, because they equally possess the property of excluding other substances from the spaces which they occupy. This, in fact, is saying no more than that two things cannot be in the same place at once, which is a self-evident truth, whether we apply it to a single particle of matter or a large mass. Every body, or portion or particle of matter, possesses a certain extension or magnitude. It is impossible to form a conception of matter, however minute may be the particle, without connecting with it the idea of its having a certain bulk, and filling a certain extent of space. In common phraseology, we express this property of bodies by the word size or volume.

The next property demanding our attention is the figure of bodies. Figure or form is the result of extension, for we cannot have the idea of a body possessing length and breadth, without its having some kind of figure, however irregular. The volume of a body has no relation to its figure. Bodies which have the same figure may possess very different volumes; and

The diffusion of particles of matter invisible to the naked eye, is also obvious in the case of the melting of a piece of sugar in our tea; the solid mass of the sugar disappears, and the particles of which it was composed are diffused in the liquid. There is a similar diffusion of particles of salt in the ocean. When we look through a glass full of sea water, we perceive that it is pure and limpid; but if we pour the water into a vessel on the fire, and boil it, we shall at length discover that, while the liquid has escaped in the form of vapour, the particles of salt it held in solution remain incrusted on the vessel.

Particles of matter are never destroyed or lost, although they may disappear from our immediate observation. Under certain circumstances, the particles may

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